Aiming at the problem of multi-objective reliability optimization for the reducer of road-rail vehicle,firstly,it must be ensured that the electric wheel planetary gear reducer is in good working order and loading conditions meet the requirements of transmission.By applying the reliability theory and optimization design technology,the reducer weight reduction,materials saving,low cost can be realized safety and reliability is improved.The MATLAB optimization toolbox is used to solve the problem of the optimization of reducer.Taking the volume and contact ratio as multi-objective optimization function,then the multi-objective optimization problem is transformed into single-objective problem to solve by the linear weighted method.The mathematical model is established by using the safety factor method and other constraints.By using Fmincon function,the optimizing calculation and analysis are carried out,the optimal solution is got,which makes the optimization design parameters more reasonable than the original design parameters.Consequently,the results show that the working performance of the electric wheel of the road-rail vehicle is improved.